Ting users: Amazon currently has a 50% off coupon for Ting GSM Sim cards. Regular price $9.00, $4.50 with coupon. Not the lowest price ever but I was glad to see a recent drop in price having bought a new BF deal phone to replace an old non-Sim Sprint phone. I selected no rush shipping to potentially give the option to cancel in case it comes up cheaper.
Ting isn't for everyone, so don't TD this just because you don't like the way it works. I'm on wifi all day and don't use much data otherwise. My family's monthly bill is usually $39.